1. Field of Invention
This invention relates generally to vehicle suspensions, and more particularly to a suspension for a flexible frame vehicle.
2. Description of Related Art
The high crop yields of modern agribusiness require application of fertilizers, pesticides, and herbicides. Dispersing these chemicals onto high acreage fields requires specialized machines mounted on or towed by a vehicle. An example of such a machine is the self-propelled crop sprayer. A common design for a self-propelled crop sprayer includes a dedicated chassis with a tank, boom arms, and nozzles connected to the boom arms. The tank contains fluid such as fertilizers, pesticides, and herbicides. Boom arms extend outward from the sides of the dedicated chassis. Boom plumbing contains supply lines and a plurality of nozzles spaced apart along the length of the boom arms at a standard spacing distance which corresponds to the spray pattern of the nozzles. In operation, as the crop sprayer crosses the field, fluid is pumped from the tank through the supply lines along the boom arms, and out through the nozzles. This allows the self-propelled sprayer to distribute the fluid along a relatively wide path. The length of conventional boom arms may vary from, for example, 6 meters (18 feet) up to 46 meters (150 feet), but smaller or longer booms are possible. The boom arms typically swing in for transport and out for operation.
Desirably, crop sprayers have a flexible suspension arrangement that permits the vehicle to traverse uneven terrain encountered in the field. One known self-propelled sprayer is provided with a suspension arrangement having each of four drive wheels of the sprayer suspended independently, one each at opposite ends of front and rear axles that are fixed to the main frame of the sprayer. The suspension for each of the wheels includes a large complicated, machined casting fixed to one end of an associated axle and which works together with spindles which telescope within upright sleeves defined by the casting so as to permit relative motion between the wheel and the axle. Another sprayer design has axles suspended from beams of the sprayer frame. The beams are fixed relative to each other by cast cross members. However, deflection of the frame concentrates stresses in the cross members and limits flexibility of the frame causing poor tire-to-ground contact in extreme terrain.
Accordingly, the problem to be solved is that of providing a wheel suspension for a self-propelled sprayer which overcomes the drawbacks associated with the prior art suspensions.